I was surprised to read your post. Did you mean that you were not aware of the first two boxes, or that you had never seen one? (I suspect the latter but am still surprised that a serious 45 Colt collector has never seen one.). They are the original packaging of the original Cal .45 (Colt length) revolver cartridges in 1873. The cartridge and the box was replaced in 1874 by the more familiar Cal .45 Revolver Ball (S&W length).
The original boxes are very rare now-a-days, but it wasn’t too long ago that they could still be found, much the same as boxes of the original Cal .45 Carbine cartridges. Boxes of the Revolver Ball cartridges can still be found from time to time on the auction sites, but having the different dates together in one sale is what makes this unusual.